NASA's Marshall Space Flight Center in Huntsville, Ala. is using a method called selective laser melting, or SLM, to create intricate metal parts for America's next heavy-lift rocket. Using this state-of-the-art technique will benefit the agency by saving millions in manufacturing costs.

Turbopump Parts

Parts for turbines and pumps are already being made using 3D printed technologies

EOS has manufactured turbine nozzle guide vanes as well as turbine impellers:

Become Familiar with the 3D printing technologies - There are various different technologies associated with producing plastic and metal parts. This Wikipedia article outlines some of the basic technologies: 3D Printing

Become familiar with 3D design technologies - In order to design a part, it must first be made as a digital 3D file. You can either contract with a design service to produce your part, or you can produce it yourself. There are CAD programs as well as 3D Design programs you can use. Some of the programs are:

Design your parts - Using either your own 3D skills or a design service, you can produce the digitial file needed to produce your parts.

Find a 3D Vendor - Although it is possible to acquire your own 3D printer for producing your parts, it is likely that you get the best short-term economy by using a 3D printing service. Here's a list of some 3D printing services. There are far more than this, so select wisely.

SUMMARY

3D printing is a technology with great promise for making rocket parts. As this Forbes Article states, it's a rapidly growing and large industry. There are many benefits that can be derived by considering using it for producing rocket parts. It can allow the production of small run parts at fairly reasonable prices.